Geraldo has already saved $40 and wants to buy a CD player for $129 in about four month.To find out how much he should save each week,he wrote 40+16*X = 129. Explain his equation.

The above project, you chose one item as the goal for your project. How much does it cost? When do you want to buy this item.

Write and solve the equation to find how much you should save per week.

Equation can be explained like this:
Geraldo has $40 already saved. He needs more money to equal $129 for CD. Lets say y is that additional amount of money that he needs. So he needs $40+y to equal 129. That y is, if he saves money for four months every week, y=16x.
So we have $40+y=$129
$40+16x=$129

To find out how much Geraldo should save in order to buy CD then equation need to be solved for x:
16x=129-40
16x=89
x=5.5625 = $5.7

So he needs to save 5.7$ each week which is 16*5.7=89$ totaly saved for four months which summed with $40 equals $129 for CD.